19's on a P85D or P85+

[commasign]

Not saying that a P85+ switching to 19" wheels gets a bump in range above 265. I'm saying that going to 19" eliminates the range loss that had occurred with using 21" wheels.

As as for the question about whether a more powerful inverter is less efficient, Tesla's official answer is no (Your Questions Answered | Tesla Motors click on the 19"/21" wheel toggle for an explanation). We know this is true for the rear motor and I'm just making the same assumption for the front motor. I.e. My theory is the front motors are all the same but the P85D just has an upgraded inverter. But who knows. Maybe it is a larger less efficient motor.

Agree with yobigd20. It all comes down to Wh/mile. The rated range is based on Tesla's own set ideal Wh/mile number (probably different for each model) which we don't have control over.

 

[HankLloydRight]

If your argument was using the same identical car, and just swapping wheels (and as it seems, not taking tires into account), then it would make more sense that you'd have a range difference of 10 up to 20-ish miles (keeping everything else the same). But in your case, you're comparing an 85D to a P85D *and* you're also changing the wheels on the P85D. That's why I think you can't compare the two models as equals. The 85D is clearly much more efficient and tuned for highest range, while the P85D is tuned for the "insane" 3.2 seconds 0-60 time, which really must take a big hit on efficiency, as reflected in the design studio. I find it really hard to believe that the only difference in range is from the wheels, and that 470hp/221hp motors in the P85D have essentially the same efficiency as the twin 188hp motors in the 85D.

Oh, and, I understand the wh/m concept, and not "rated range" and the effects from temp. For the sake of the discussion, I'm assuming all other things being equal.

- - - Updated - - -

As as for the question about whether a more powerful inverter is less efficient, Tesla's official answer is no (Your Questions Answered | Tesla Motors click on the 19"/21" wheel toggle for an explanation).

I don't see the connection between the wheel size and inverter size on that page. I think you are incorrectly assuming that when clicking "21" that the site is assuming a different inverter size. I'm sure that's not happening as it just says "Range decreases slightly with larger wheels. 21" wheels have more contact with the road and are made of stickier rubber. Both characteristics increase friction.". How do you get a change in inverter size from that?

edit: Perhaps you mean the Vehicle Switch, where it says:

Model S Performance accelerates from 0 to 60 MPH in 4.2 seconds. But, if driven the same way as a Model S, both cars achieve the same efficiency.

I didn't say anything about the inverter being more/less efficient.. I'm talking about the two motors being less efficient. The comment above is true about the different inverters, but the motors between the 85 and P85 are identical, so "if driven the same" their efficiency is the same.

The motors between 85D and P85D are not the same.

 

[commasign]

Sorry, typo about the toggle.

I guess the real question is whether the front motor in the P85D, if driven in the same way, is also as efficient as the front motor in the 85D. My reasoning for this ignores the contribution of the rear motor so in that sense the logic is flawed, but think of it this way. Elon described 3 modes for the P85D, normal, sport, and insane. If normal mode basically relies only on the front motor at cruising speed and light acceleration, then in theory it should be as efficient as the 85D (ignoring differences in weight and differences due to tuning for performance). I agree that any usage of the rear motor will decrease efficiency compared to the 85D. So maybe 285 miles is more realistic. I guess this is something that Tesla can continuously improve with software as time goes on. Apparently the car only needs 14 HP to maintain 65mph speed so it would make sense that the rear motor is basically off when cruising. Again, I'm making the assumption that there is some sort of Eco sweet spot where the front motor of the P85D is similar in efficiency to the front motor of the 85D, and the rear motor is sleeping.

 

[commasign]

The website has been updated and we now have our answer. The base P85D now comes with 19" standard wheels, raising the rated range from 275 miles up to 285 miles. So basically, the range penalty as compared to the 85D is just 10 miles. Not bad for almost twice the horsepower and torque and 2 seconds faster 0-60mph.

 

[Cottonwood]

The website has been updated and we now have our answer. The base P85D now comes with 19" standard wheels, raising the rated range from 275 miles up to 285 miles. So basically, the range penalty as compared to the 85D is just 10 miles. Not bad for almost twice the horsepower and torque and 2 seconds faster 0-60mph.

Interesting, but when you upgrade to the 21" wheels, the P85D range does not drop back to 275...

I believe the 10 mile range difference between 19's and 21's. That is about what I see on my Sig P85.

 

[commasign]

The order page rated range doesn't have to drop since it's already mentioned in the fine print. Kind of sneaky I think. But I can see how that might discourage too many people from ordering 21's if it did drop.

 

[jweinstein]

What kind of performance loss is reasonably expected (if any) on a P85D using 19" wheels/tires compared to the 21"s? Specifically, I'm thinking of 0-60 times and the 1/4 mile.

Thanks!
Josh

 

[LetsGoFast]

Straight line performance (0-60 and 1/4 mile) is not noticably affected by the diameter of the tire. The real difference between tires would be on cornering and slalom performance. What would affect 0-60 time is the stickiness of the tire -- the softer and stickier the rubber, the less slippage and the better your launch will be. The traction control system will compensate, but it will slow you down. The Goodyears would be slower than the Primacys (speed rating is a pretty good analog for stickiness). I'd expect the 0-60 between Primacys and the stock 21s to be essentially identical. In fact, I believe that the 19 inch wheels are slightly lighter, so they might actually be a smidge faster.

 

[yobigd20]

What kind of performance loss is reasonably expected (if any) on a P85D using 19" wheels/tires compared to the 21"s? Specifically, I'm thinking of 0-60 times and the 1/4 mile.

Straight line performance (0-60 and 1/4 mile) is not noticably affected by the diameter of the tire. The real difference between tires would be on cornering and slalom performance. What would affect 0-60 time is the stickiness of the tire -- the softer and stickier the rubber, the less slippage and the better your launch will be. The traction control system will compensate, but it will slow you down. The Goodyears would be slower than the Primacys (speed rating is a pretty good analog for stickiness). I'd expect the 0-60 between Primacys and the stock 21s to be essentially identical. In fact, I believe that the 19 inch wheels are slightly lighter, so they might actually be a smidge faster.

100% agree. I would expect that a proper aftermarket 19" that has enough grip (aka something like my Michelin Pilot Sport A//S 3) would be slightly faster than the OEM 21s due to lighter wheels and less rotational mass and slightly less resistance (narrower contact patch). So from a purely technical perspective, less rotational mass = faster. It's not really noticeable though. Maybe something like 0.1s faster on a quarter mile.

There are many other benefits and reasons to choose 19s over 21s instead of trying to convince yourself with 0-60 or 1/4 mile times.

- Smoothness (you don't feel every bump on the road),

- quietness (you don't hear lots of road noise),

- much much longer tread life (2x-10x longer YMMV),

- safety - better for snow/wet weather (low profile summer performance are like ice skates in winter, do not drive them during winter!),

- they are less prone to blowouts or rim damage on potholes (due to larger sidewall that can absorb potholes without sustaining damage). therefore, no inconveniences with towing, rentals, etc as the MS doesn't carry a spare tire.

- COST (the tires are much cheaper [well, not so for my PS A/S 3], but still combine that cost with them lasting 2x-10x longer it is order of magnitudes cheaper over the vehicle's lifetime).

Frankly I went wider with 255s on my 19s so I do have a bit larger contact patch. I wanted all the benefits that I just listed without sacrificing handling (hard cornering).

After doing my research I chose the PS A/S 3 ( Pilot Sport A/S 3 | Michelin Tires ) due to all the exceptional reviews. After reading many many reviews on the tire they all seem to be in agreement and it has 4.5-5 star ratings everywhere from reviews and actual customers. It's an all season tire that outperforms summer tires. really best of all world's here. Here's one:

Michelin Puts Its New Pilot Sport A/S 3 To The Test | car News @ Top Speed

With exception to us southern-state dwellers, you need a set of tires that can handle the rain, snow and ice that the winter, fall and spring present us, and most summer tires simply can’t handle the elements. Well, Michelin has an all-new all-season tire that packs summer tire-like stickiness with an all-season design and features: the Pilot A/S 3.

This all-new Pilot Sport tire uses a special blend of silica to help enhance the "sticky" feeling of the tire and a tread design that helps jettison water from under your car’s footprint. The combination of water channeling and extra silica really helps the tire bite down on the road. Additionally, variable-thickness sipes on the outer section of the tread help break up the tension in the water and then lock together to create maximum rubber contact to the asphalt.

When it comes to tires, you cannot base purchasing decisions on sheer performance, unless you have tons of money to blow. You also have to consider how long the manufacture guarantees the tire will last. Most summer tires don’t include a mileage warranty and most all-season tires with any sort of warranty are too hard to perform well. Michelin obviously found a nice balance with the Pilot A/S 3,as these shoes come with a 45,000-mile warranty.

A truly unique feature on the A/S 3 that surprises even me - a seasoned expert in the tire industry - is Michelin’s Helio Compound, which helps the rubber retain its soft and sticky properties in cold temperatures. This is a frequent complaint of all-season tire users, as it can take seemingly forever for your tires to get up to temperature on a cold day. Not only does this increase cold-weather grip, but it also increases comfort in cold weather.

 

[xy46]

I have an S85D on order but am seriously considering upgrading to the P85D with 19" wheels. I love the ride quality of the S85 with coil suspension and 19" wheels and am wondering how much "rougher" or harsh the ride will be in a P85D with 19" wheels and coil suspension since the suspension is based on the P85+?